Area marked Y involves mold filling with minerals and sediment.
Answer: Option D
Step-by-step explanation:
Mold and cast are the 3-D impressions on the surface where an organism is preserved. These organisms will start decaying leaving a pit that looks exactly like the organisms' impression. This space will be filled with materials like sediments and minerals. The filling materials are known as mold thus forms the cast on the impression.
Later the organism's remaining will get decomposed completely and the sediment around it as mold gets hardened by water. This hardened sediment in the imprint that contains the structure of the decomposed organism.